Patrick McLoughlin, the transport secretary, has said he is comfortable with plans to pay senior executives on the HS2 rail project more than the prime minister.

It follows claims by the head of HS2, Sir David Higgins, that he intends to pay as many as 30 people more than David Cameron's salary of £140,000 a year.

The coalition government has repeatedly said public servants should not earn more than the prime minister, and has imposed pay restraints upon nearly all public sector workers.

Interviewed on BBC Radio Derby, McLoughlin said the salaries "fell within the budget we've set" but that he now had to get Treasury clearance.

"It has to go through a procedure. I have to get clearance from the Treasury. I'm OK with that," he said.

He said Higgins was a "world-renowned engineering expert and has done some incredible public work" and the public servants in question were "engineers at the height of their skills who would be paid a lot more in the private sector".

Higgins told BBC Newsnight on Thursday that paying more was "absolutely essential" to get the right people now rather than when problems developed, and that he would ask for permission to break the rules.

Higgins, the project's chairman, said the worst money to save was "skimping on hiring the best people".

"I am determined that we hire the best people. We are not going to pay over the odds – we probably won't even pay what the private sector would pay."

He added: "We have to have the flexibility to pay the right people now rather than when something gets in to a problem in years to come.

"We've got to remember we are hiring project people, project people that will be held accountable for performance. If they don't perform they'll go."

The first phase of HS2, between London and Birmingham, is due for completion in 2026, with a second Y-shaped section from Birmingham to Manchester and Leeds due to be finished in 2032-33.

The cost of the project in its entirety is estimated at £42.6bn, of which £14.56bn is contingency. A further £7.5bn is needed for the high-speed trains.

Earlier this week, MPs began the process of scrutinising nearly 2,000 objections to the HS2 bill. A committee of six MPs will spend months, perhaps years, listening to evidence from those who will be affected by the project.

The fate of the scheme will be eventually decided by a vote of all MPs.

A spokeswoman for the prime minister warned that any change would have to be approved by the Treasury.